Thanks for the feedback so far!
Drawing a darker outline around part only part of the sprite looks a bit odd - I'd remove them altogether.
Hmm... I'll mess with that a little and see if I can figure out a way to make it work better.
What some people do is to create a mockup in paint-shop-pro. ie, a composition of graphics that looks like a screenshot of your game would look. These can be very helpful to determine if your graphics are harmonious and work together. It can also be very useful to determine how your game screen will be set out and the sizes of different things.
That sounds like a good idea. I'll have to try that.
One thing I noticed is a lack of contrast in particular in the middle of the sprite so I made this real quick edit to show how I think you can improve some things the main points being contrast, definition, and colors. This may or not have been your intent for what it to look like but, take what you will from it. Hope it helps.
Oh, I see what you mean. That does help. Thanks!